I don't trust a forecast at all. My place is notorious for missing out on rains. I couldn't even begin to tell you how many times this year I have had good storm fronts coming only to have it split just West of me sometimes within a mile and miss me entirely only to come back together just to the East. It really is uncanny and very depressing. I will sit and look at the radar and tell my wife there is no way this one is going to miss us but it sure enough usually does.
I have lost plantings before because of sure bets on rain that didn't come. Now I try and plant everything at the proper times to reduce my losses.